Prof. Miller on the Imperial Standard Pound, 545 



^ With the single exception of K, all the brass weights have become 

 n heavier since they were compared with U, in consequence probably 

 3iof the oxidation of their surfaces, while U, which was made in 1758, 



- was protected from further change by the coat of oxide already 

 h formed. One of these weights, Sb, appeared to have been protected 

 ^ by gilding, though imperfectly, since parts of its surface were slightly 

 K'rtarnished. Ex and L were brighter than Ed and D. K, though it 

 t^had become lighter, was much tarnished. The discordances pre- 

 . fflented by the different weighings of K appear to have greatly per- 

 .■)plexed both Professor Schumacher and Captain Kater, and were 

 Siiprobably the cause of the numerous and accurate comparisons of the 



- ^several troy pounds placed at the disposal of the Committee with the 

 -blost standard, on which alone depends the possibiHty of restoring it 



'; with sufficient accuracy. Previous to the comparison of K in 1844, 

 ; a small fragment of wood, like a grain of coarse sawdust, was found 

 .adhering so firmly to its under surface, that it was detached with 

 ■ some difficulty. It appears probable that the changes of the weight 

 iiof K were caused by this bit of wood being weighed with it after 

 4 the first comparison of K by Captain Kater, and by the gradual 

 -r oxidation of the surface of K. The discrepancies presented by the 

 /♦weighings of the brass troy pounds at different times, due to the 

 is effect of oxidation or other causes, are so large, that I resolved, with 

 ;,ithe consent of the Astronomer Royal, to rest for the evidence of the 

 weight of the lost standard entirely on the 300 comparisons of Sp 

 ^ and the 140 comparisons of RS with U. 



If we consider the discordances presented by the weighings of the 

 i brass troy pounds simply as errors of observation, without paying 

 ,( any regard to their probable causes, the resulting value of U will not 

 I be very different from that given by the platinum troy pounds alone. 

 t! By the observations of 1824 and 1829, 



hmojl £i:-.v ,0u ou:- gr. jJ^ ,^ji ^.iveaghfc^ilgisy? 



U=Sp 4-0-0081 „ov r ctI 30^ij5iij 



U=RS +0-0030,^" 14 



,rU=Sb :^.^m +0-0103. 04. Cf8=8a6 



rU=K -0-0339=0+ d8=:qf^ 9 



< U=KEx + L + Ed + D)-0-0022.o+ d8=:aa.6 

 By the observations of 1844, u^-iO'0+ q8~ JA. 



tiso-#d«=. ii =sp +0-0057, :a 



u , A »%-f. A =SP +0-0030^ . . _ 



oil? n'iaw:>9d soirj^tiD ^Ai _g^ +0-0363^*^^ ^" ^^ 



.imrr^wori ^frog^_^Ed + D=:2(Sb + K) + 0-02G0^"^^^"^'f^ ^^* 



"Whence, supposing the errors of weighing in 1844 to be insensible, 

 !,' co?^pared with the discordances of the brass troy pounds,,^| -^ |,^, 



'"'^ gr. weight. ^A 



(1) U=Sp + 0-0081 30 , . '^^" 



"^h ''"^m U=Sp + 0-0087 14 ■ ^^ 



m C'Booo (|a U=Sp+0-0i33 i»hM«6^ r^--ir~ xa 



OS bmrOQk) u=Sp+o-oo24 ^'^<>«$+=-5^- ^j; 



- ' (5) U=Sp + 0-0261 '■ " (i ~ ^ -yl ^ 



The mean of all the equations gives U=Sp-|-0'0096 graim^Mg 



